Dr. Neal Barnard may come from a family of cattle ranchers, but he's got a beef against meat. For 19 years, the founder of the Physicians Committee for Responsible Medicine has preached the virtues of veganism, accusing parents of "child abuse" if they feed their kids so much as a slice of bacon and calling the Atkins-diet logo, a red A, "the scarlet letter." PCRM is a sort of anti-Atkins foundation, with attention-grabbing press conferences and a list of patients who blame the meaty diet for their poor health. So it's no surprise that in the carb war's latest skirmish, Barnard is the attacking general.

What is surprising, though, is PCRM's new battle strategy. Last week, after years of conventional scientific warfare, the group went guerrilla, leaking to The Wall Street Journal a copy of a New York City medical examiner's report on Dr. Robert Atkins's death from a fall last April. The report said the 6-foot Atkins weighed 258 pounds and had congestive heart failure, hypertension and an "MI": shorthand for a heart attack. One of his arteries was also blocked. Barnard says he knew his staff was talking to reporters, but claims he didn't expect the Journal to publish the report. But by the next news cycle, Dr. Atkins was making as many headlines as he did when he died--less tactful papers were calling him "Dr. Fatkins."

The report is less sensational than the media frenzy suggested. There's no insinuation that Atkins's heart trouble led to his death (despite the public speculation, of New York City Mayor Michael Bloomberg and others, that it was somehow involved). Dr. Stuart Trager, chair of the Atkins Physicians Council, says the "MI" is an inaccurate reference to Atkins's 2002 cardiac arrest, blamed on a rare viral condition. The weight in the report qualified Atkins as obese, but hospital records list a reported weight of 195 pounds. According to the report, his legs swelled during his eight-day coma. Swelling usually accounts for 10 or so pounds, but Dr. Keith Berkowitz--Atkins's internist and colleague, who was with him at the hospital--says he has seen coma patients gain 30 pounds in a day. Other doctors disagree, but he says "without a doubt" the extra pounds were largely water weight. And he adds that dieters should focus on science, not an individual's health--a point echoed even by docs who oppose low-carb diets.

The exposure of Atkins's death report by PCRM incenses his associates. Releasing data without patient or family consent may violate federal law, and the New York ME's office has complained to Nebraska authorities about Dr. Richard Fleming, a cardiologist from Omaha who obtained the report. (He is believed to have sent it to PCRM's headquarters.) For his part, Barnard says the Atkins Foundation put the diet guru up for grabs. "It's regrettable when someone's medical history goes public," he says. "But they exploited him for years as a poster child for cardiovascular health, and the truth was very different." Trager disagrees. "What they did reeks of vigilantism," he says. The matter of a lawsuit is up to Atkins's widow--but the foundation is watching Nebraska.

If Atkins's associates do sue PCRM, things could get a lot uglier. Less than 5 percent of PCRM's members are physicians. And Barnard has co-signed letters, on PCRM letterhead, with the leader of Stop Huntingdon Animal Cruelty, an animal-rights group the Department of Justice calls a "domestic terrorist threat." PCRM also has ties to People for the Ethical Treatment of Animals. An agency called the Foundation to Support Animal Protection has distributed money from PETA to PCRM in the past and, until very recently, did both groups' books. Barnard and PETA head Ingrid Newkirk are both on the foundation's board.

But Barnard insists "nobody with an IQ over room temperature" would think the group's stand against animal research influences its views on Atkins. "Our stance is the mainstream stance," he says. Many docs doubt the diet's safety, and though short-term studies appear favorable, there are no long-term studies. Barnard says the data--plus a few possibly related deaths and his own growing registry of patient complaints--convinced him the diet was dangerous. Some patients want to sue their doctors, and PCRM is "willing to provide information" to help, he says. The next battleground may be the courtroom.